In this paper we introduced the shielding region concept in order to relieve the electric field concentrated on the trench bottom corner. The shielded trench gate insulated gate bipolar transistor (IGBT) is a trench gate IGBT with a P+shielding region located in the bottom of a trench gate. By simulation results, we verified that a shielding region reduced the electric fields not only in the gate oxide but also in the P-base region. Compared with conventional trench gate IGBT, about 33% increment of forward breakdown voltages are achieved, but little forward voltage drop, which causes on-state loss to be increased by about 0.06V in the shielded trench gate IGBT.